無效函數錯誤（不使用計算的值）

Question

大家好我已經嘗試了我的代碼的幾個變體，我無法弄清楚如何解決這些警告。

• 的目標是在C創建蒙提霍爾問題的模表示

問題

• 我outputFinalResult功能無法給我正確的輸出

個錯誤消息

- gcc -Wall monteball.c 

monteball.c: In function ‘determineOutcomeStay’: 

monteball.c:125:7: warning: value computed is not used [-Wunused-value] 

monteball.c:127:3: warning: value computed is not used [-Wunused-value] 

monteball.c: In function ‘determineOutcomeSwitch’: 

monteball.c:134:7: warning: value computed is not used [-Wunused-value] 

monteball.c:136:3: warning: value computed is not used [-Wunused-value] 

monteball.c: In function ‘getFinalChoice’: 

monteball.c:119:1: warning: control reaches end of non-void function [-Wreturn-type] 

順便說一句，我應該擔心這個警告呢？

代碼

void outputFinalResult (int winStay, int winSwitch, int stayCount, int switchCount); 
//function is 4 print statements using arguments calculated by determineOutcome functions 
int main (int argc, char * argv []) 
{ 
    srand(time(NULL)); 
    int counter = 10000; 
    int i = 0; 
    int winStay; 
    int winSwitch = 0; 
    int stayCount; 
    int switchCount = 0; 
    int firstChoice; 
    int grandPrize; 
    int revealedDoor; 
    int finalChoice; 

    for (i = 0; i < counter; i++) 
    { 
    firstChoice = getUserChoice(); 

    grandPrize = determinePrizeLocation(); 

    revealedDoor = revealDoor (firstChoice, grandPrize); 

    finalChoice = getFinalChoice (firstChoice, grandPrize, revealedDoor); 

    if(finalChoice == firstChoice) 
    { 
     determineOutcomeStay(finalChoice, grandPrize, &winStay, &stayCount); 
    } else 
    { 
     determineOutcomeSwitch(finalChoice, grandPrize, &winSwitch, &switchCount); 
    } 

    } 

    outputFinalResult (winStay, winSwitch, stayCount, switchCount); 
    return 0; 
} 
int getFinalChoice (int firstChoice, int grandPrize, int revealedDoor) 
{ 
    int finalChoice; 
    int switchProbability = rand() % 2 + 1; // 50% chance of keeping or switching choice                        

    if (switchProbability == 1) // Represents user keeping their choice                            
    { 
    return firstChoice; 
    } 

    else if (switchProbability == 2) // Represents user switching their choice                          
    { 
    finalChoice = rand() % 3 + 1; // Randomizes finalChoice btw 1-3                            

    while (finalChoice == revealedDoor || finalChoice == firstChoice) // Ensures that finalChoice isn't the door that was eliminated or           
    {                 // the door that was initially selected                 
     finalChoice = rand() % 3 + 1; 
    } 

    return finalChoice; 
    } 
} 

void determineOutcomeStay(int choice, int grandPrize, int * winStay, int * stayCount) 
{ 
    if(choice == grandPrize) 
    { 
    *winStay++; 
    } 
*stayCount++; 
} 

void determineOutcomeSwitch(int choice, int grandPrize, int * winSwitch, int * switchCount) 
{ 
    if(choice == grandPrize) 
    { 
    *winSwitch++; 
    } 
    *switchCount++; 
} 

對不起，長的帖子只是想給所有的信息需要得到一個很好的答案。如果需要其他信息，請通知我。謝謝。

Answer 1

大多數警告你想解決，他們很擅長髮現不良行爲。你的具體情況：

線

*stayCount++; 

不會做你的想法。 Operator precedence表示在這種情況下++首先出現。人機工程學實際上就意味着這一點：

*(stayCount++); 

這樣的警告，stayCount改變，但沒有使用。把括號周圍可能是不明確的任何表情，這是那個時代

(*stayCount)++; 

在getFinalChoice錯誤是自explanitory之一，「控制到達非void函數的末尾」。換句話說，有一條通過函數的路徑，不會導致return被調用。我會讓你找到它;）